Method and apparatus for high rate data transmission in wireless communication

ABSTRACT

Techniques for utilizing multiple carriers to substantially improve transmission capacity are described. For multi-carrier operation, a terminal receives an assignment of multiple forward link (FL) carriers and at least one reverse link (RL) carrier. The carriers may be arranged in at least one group, with each group including at least one FL carrier and one RL carrier. The terminal may receive packets on the FL carrier(s) in each group and may send acknowledgements for the received packets via the RL carrier in that group. The terminal may send channel quality indication (CQI) reports for the FL carrier(s) in each group via the RL carrier in that group. The terminal may also transmit data on the RL carrier(s). The terminal may send designated RL signaling (e.g., to originate a call) on a primary RL carrier and may receive designated FL signaling (e.g., for call setup) on a primary FL carrier.

CLAIM OF PRIORITY UNDER 35 U.S.C. §119

The present application for patent claims priority to ProvisionalApplication Ser. No. 60/666,461, entitled “METHOD AND APPARATUS FOR HIGHRATE DATA TRANSMISSION IN WIRELESS COMMUNICATIONS,” filed Mar. 29, 2005,assigned to the assignee hereof, and expressly incorporated herein byreference.

BACKGROUND

I. Field

The present disclosure relates generally to communication, and morespecifically to techniques for high rate data transmission.

II. Background

Wireless communication systems are widely deployed to provide variouscommunication services such as voice, packet data, broadcast, messaging,and so on. These systems may be multiple-access systems capable ofsupporting communication for multiple users by sharing the availablesystem resources. Examples of such multiple-access systems include CodeDivision Multiple Access (CDMA) systems, Time Division Multiple Access(TDMA) systems, Frequency Division Multiple Access (FDMA) systems, andOrthogonal Frequency Division Multiple Access (OFDMA) systems.

Data usage for wireless communication systems continually grows due toincreasing number of users as well as emergence of new applications withhigher data requirements. However, a given system typically has limitedtransmission capacity, which is determined by the design of the system.A substantial increase in transmission capacity is often realized bydeploying a new generation or a new design of a system. For example, thetransition from second generation (2G) to third generation (3G) incellular systems provides substantial improvements in data rate andfeatures. However, new system deployment is capital intensive and oftencomplicated.

There is therefore a need in the art for techniques to improvetransmission capacity of a wireless communication system in an efficientand cost effective manner.

SUMMARY

Techniques for utilizing multiple carriers on the forward and/or reverselink to significantly improve transmission capacity are describedherein. These techniques may be used for various wireless communicationsystems such as, e.g., a cdma2000 system. These techniques may providevarious benefits with relatively minor changes to existing channelstructures designed for single-carrier operation.

According to an embodiment of the invention, an apparatus is describedwhich includes at least one processor and a memory. The processor(s)receive an assignment of multiple forward link (FL) carriers and atleast one reverse link (RL) carrier. The processor(s) thereafter receivedata transmission on one or more of the multiple FL carriers.

According to another embodiment, a method is provided in which anassignment of multiple FL carriers and at least one RL carrier isreceived. Data transmission is thereafter received on one or more of themultiple FL carriers.

According to yet another embodiment, an apparatus is described whichincludes means for receiving an assignment of multiple FL carriers andat least one RL carrier, and means for receiving data transmission onone or more of the multiple FL carriers.

According to yet another embodiment, an apparatus is described whichincludes at least one processor and a memory. The processor(s) obtainacknowledgements for packets received on multiple data channels (e.g.,F-PDCHs), channelize the acknowledgement for each data channel with anorthogonal code assigned to the data channel to generate a symbolsequence for the data channel, and generate modulation symbols for anacknowledgement channel (e.g., R-ACKCH) based on the symbol sequencesfor the multiple data channels.

According to yet another embodiment, a method is provided in whichacknowledgements are obtained for packets received on multiple datachannels. The acknowledgement for each data channel is channelized withan orthogonal code assigned to the data channel to generate a symbolsequence for the data channel. Modulation symbols for an acknowledgementchannel are generated based on the symbol sequences for the multipledata channels.

According to yet another embodiment, an apparatus is described whichincludes means for obtaining acknowledgements for packets received onmultiple data channels, means for channelizing the acknowledgement foreach data channel with an orthogonal code assigned to the data channelto generate a symbol sequence for the data channel, and means forgenerating modulation symbols for an acknowledgement channel based onthe symbol sequences for the multiple data channels.

According to yet another embodiment, an apparatus is described whichincludes at least one processor and a memory. The processor(s) obtainfull channel quality indication (CQI) reports for multiple FL carriers,with each full CQI report indicative of received signal quality for oneFL carrier. The processor(s) send the full CQI reports for the multipleFL carriers in different time intervals on a CQI channel (e.g.,R-CQICH).

According to yet another embodiment, a method is provided in which fullCQI reports for multiple FL carriers are obtained, with each full CQIreport indicative of received signal quality for one FL carrier. Thefull CQI reports for the multiple FL carriers are sent in different timeintervals on a CQI channel.

According to yet another embodiment, an apparatus is described whichincludes means for obtaining full CQI reports for multiple FL carriers,with each full CQI report indicative of received signal quality for oneFL carrier, and means for sending the full CQI reports for the multipleFL carriers in different time intervals on a CQI channel.

According to yet another embodiment, an apparatus is described whichincludes at least one processor and a memory. The processor(s) operatein a control-hold mode that allows for transmission of a gate pilot,receive a data channel (e.g., P-PDCH) sent on the forward link while inthe control-hold mode, transmit a gated pilot on a reverse link if noother transmissions are being sent on the reverse link, and transmit afull pilot on the reverse link if a transmission is being sent on thereverse link.

According to yet another embodiment, a method is provided in which aterminal is operated in a control-hold mode that allows for transmissionof a gate pilot. A data channel sent on a forward link is received whilein the control-hold mode. A gated pilot is transmitted on the reverselink if no other transmissions are being sent on the reverse link. Afull pilot is transmitted on the reverse link if a transmission is beingsent on the reverse link.

According to yet another embodiment, an apparatus is described whichincludes means for operating in a control-hold mode that allows fortransmission of a gated pilot, means for receiving a data channel senton the forward link while in the control-hold mode, means fortransmitting a gated pilot on the reverse link if no other transmissionsare being sent on the reverse link, and means for transmitting a fullpilot on the reverse link if a transmission is being sent on the reverselink.

Various aspects and embodiments of the invention are described infurther detail below.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a wireless communication system.

FIG. 2 shows an exemplary data transmission on the forward link incdma2000.

FIG. 3 shows an exemplary multi-carrier structure.

FIG. 4A shows an R-ACKCH structure in cdma2000 revision D.

FIGS. 4B and 4C show a new R-ACKCH structure that can support up tothree and seven R-ACKCHs, respectively, for multiple FL carriers.

FIG. 5A shows an R-CQICH structure in cdma2000 revision D.

FIG. 5B shows a new R-CQICH structure that can support multiple FLcarriers.

FIGS. 6A through 6E show exemplary transmissions on the new R-CQICH.

FIG. 7 shows transmission of full and gated pilots on an R-PICH.

FIG. 8 shows a process performed by a terminal for multi-carrieroperation.

FIG. 9 shows a process for sending acknowledgements.

FIG. 10 shows a process for sending CQI reports.

FIG. 11 shows a process for reducing pilot overhead for multi-carrieroperation.

FIG. 12 shows a block diagram of a base station and a terminal.

DETAILED DESCRIPTION

The word “exemplary” is used herein to mean “serving as an example,instance, or illustration.” Any embodiment described herein as“exemplary” is not necessarily to be construed as preferred oradvantageous over other embodiments.

FIG. 1 shows a wireless communication system 100 with multiple basestations 110 and multiple terminals 120. A base station is generally afixed station that communicates with the terminals and may also bereferred to as an access point, a Node B, a base transceiver subsystem(BTS), and/or some other terminology. Each base station 110 providescommunication coverage for a particular geographic area 102. The term“cell” can refer to a base station and/or its coverage area depending onthe context in which the term is used. To improve system capacity, abase station coverage area may be partitioned into multiple smallerareas, e.g., three smaller areas 104 a, 104 b, and 104 c. The term“sector” can refer to a fixed station that serves a smaller area and/orits coverage area depending on the context in which the term is used.For a sectorized cell, a base station typically serves all sectors ofthe cell. The transmission techniques described herein may be used for asystem with sectorized cells as well as a system with un-sectorizedcells. For simplicity, in the following description, the term “basestation” is used generically for a fixed station that serves a sector aswell as a fixed station that serves a cell.

Terminals 120 are typically dispersed throughout the system, and eachterminal may be fixed or mobile. A terminal may also be referred to as amobile station, a user equipment, or some other terminology. A terminalmay be a cellular phone, a personal digital assistant (PDA), a wirelessdevice, a handheld device, a wireless modem, and so on. A terminal maycommunicate with zero, one, or multiple base stations on the forwardand/or reverse link at any given moment. The forward link (or downlink)refers to the communication link from the base stations to theterminals, and the reverse link (or uplink) refers to the communicationlink from the terminals to the base stations.

A system controller 130 couples to base stations 110 and providescoordination and control for these base stations. System controller 130may be a single network entity or a collection of network entities.

The transmission techniques described herein may be used for variouswireless communication systems such as CDMA, TDMA, FDMA and OFDMAsystems. A CDMA system may implement one or more radio technologies suchas cdma2000, Wideband-CDMA (W-CDMA), and so on. cdma2000 covers IS-2000,IS-856, IS-95, and other standards. A TDMA system may implement a radiotechnology such as Global System for Mobile Communications (GSM). Thesevarious radio technologies and standards are known in the art. W-CDMAand GSM are described in documents from a consortium named “3rdGeneration Partnership Project” (3GPP). cdma2000 is described indocuments from a consortium named “3rd Generation Partnership Project 2”(3GPP2). 3GPP and 3GPP2 documents are publicly available. For clarity,the transmission techniques are specifically described below for acdma2000 system, which may be a “CDMA 1x-EVDV”, “CDMA 1x”, “CDMA1x-EVDO” and/or “1x” system.

cdma2000 defines various data and control channels that support datatransmission on the forward and reverse links. Table 1 lists some dataand control channels for the forward and reverse links and provides ashort description for each channel. In the description herein, prefix“F-” denotes a channel for the forward link and prefix “R-” denotes achannel for the reverse link. The channels are described in detail in“TIA/EIA IS-2000.2 Physical Layer Standard for cdma2000 Spread SpectrumSystems, Release D” (hereinafter, TIA/EIA IS-2000.2) and “TIA/EIAIS-2000.3 Medium Access Control (MAC) Standard for cdma2000 SpreadSpectrum Systems, Release D” (hereinafter, TIA/EIA IS-2000.3), both fromTelecommunications Industry Association, dated 2004, and publiclyavailable. cdma2000 revision D is also referred to as IS-2000 revisionD, or simply “Rev D”. The data and control channels are also describedin other standard documents for cdma2000.

TABLE 1 Link Channel Description Forward F-PDCH Forward Packet DataChannel - used to send Link packet data to specific terminals in a timedivision multiplexed (TDM) manner. F-PDCCH Forward Packet Data ControlChannel - carries control data for an associated F-PDCH. F-ACKCH ForwardAcknowledgement Channel - carries feedback for transmissions received onthe R-PDCH. F-GCH Forward Grant Channel - used by a base station togrant a terminal permission to transmit on the R-PDCH. Reverse R-PDCHReverse Packet Data Channel - used to send Link packet data to a basestation. R-ACKCH Reverse Acknowledgement Channel - carries feedback fortransmissions received on the F-PDCH. R-CQICH Reverse Channel QualityIndication Channel - carries channel quality measurements for theforward link. R-PICH Reverse Pilot Channel - carries a pilot on thereverse link. R-REQCH Reverse Request Channel - used by a terminal torequest a higher data rate for the R-PDCH.

In general, the F-PDCH, F-PDCCH, R-ACKCH and R-CQICH are used for datatransmission on the forward link. The R-PDCH, R-REQCH, R-PICH, F-ACKCHand F-GCH are used for data transmission on the reverse link. Ingeneral, each channel may carry control information, data, pilot, othertransmission, or any combination thereof.

FIG. 2 shows an exemplary data transmission on the forward link incdma2000. A base station has data packets to send to a terminal. Thebase station processes each data packet to generate a coded packet andfurther partitions the coded packet into multiple subpackets. Eachsubpacket contains sufficient information to allow the terminal todecode and recover the packet under favorable channel conditions.

The base station transmits the first subpacket A1 for packet A on theF-PDCH in two slots starting at time T₁. A slot has a duration of 1.25milliseconds (ms) in cdma2000. The base station also transmits on theF-PDCCH a 2-slot message that indicates that the transmission on theF-PDCH is for the terminal. The terminal receives and decodes subpacketA1, determines that packet A is decoded in error, and sends a negativeacknowledgement (NAK) on the R-ACKCH at time T₂. In this example, theACK delay is 1 slot. The base station transmits the first subpacket B1for packet B on the F-PDCH in four slots starting at time T₃. The basestation also transmits on the F-PDCCH a 4-slot message that indicatesthat the transmission on the F-PDCH is for the terminal. The terminalreceives and decodes subpacket B1, determines that packet B is decodedcorrectly, and sends an acknowledgement (ACK) on the R-ACKCH at time T₄.The base station transmits the second subpacket A2 for packet A on theF-PDCH in one slot starting at time T₅. The terminal receives subpacketA2, decodes subpackets A1 and A2, determines that packet A is decoded inerror, and sends a NAK on the R-ACKCH at time T₆.

The terminal also periodically measures the channel quality for basestations that can potentially transmit data to the terminal. Theterminal identifies the best base station and sends full anddifferential (Diff) channel quality indication (CQI) reports on theR-CQICH, as described below. The CQI reports are used to select the mostsuitable base station to send data to the terminal as well as a suitabledata rate for data transmission.

In cdma2000, a base station spectrally spreads data with a pseudo-randomnumber (PN) sequence at a rate of 1.2288 megachips/second (Mcps). Thebase station modulates a carrier signal with the spread data andgenerates a radio frequency (RF) modulated signal having a bandwidth of1.2288 MHz. The base station then transmits the RF modulated signal at aspecific center frequency on the forward link. This is referred to assingle-carrier CDMA since a single carrier is modulated with data. Thecapacity of the forward link is determined by the number of data bitsthat may be reliably sent in the 1.2288 MHz RF modulated signal. On thereverse link, a terminal also spectrally spreads data with a PN sequenceat 1.2288 Mcps and transmits the spread data at a specific carrierfrequency. The capacity of the reverse link is determined by the numberof data bits that may be reliably sent on a data channel assigned to theterminal.

In an aspect, multiple carriers are utilized on a link to achievesignificant capacity improvement on that link. In an embodiment, a chiprate of 1.2288 Mcps is used for each of the multiple carriers, which isthe same chip rate used for single-carrier CDMA. This allows hardwaredesigned for single-carrier CDMA to also support multi-carrier CDMA.

FIG. 3 shows a diagram of an embodiment of a multi-carrier structure300. In this embodiment, K carriers are available on the forward link,and M carriers are available on the reverse link, where K>1 and M≧1. Aforward link (FL) carrier is a carrier on the forward link, and areverse link (RL) carrier is a carrier on the reverse link. A carriermay also be referred to as an RF channel, a CDMA channel, and so on. TheK FL carriers and M RL carriers are arranged in G groups, where G≧1. Ingeneral, any number of carrier groups may be formed, and each group mayinclude any number of FL carriers and any number of RL carriers.

In the embodiment shown in FIG. 3, each carrier group includes at leastone FL carrier and one RL carrier, so that G=M and K≧M. As shown in FIG.3, carrier group 1 includes FL carriers 1 through N₁ and RL carrier 1,carrier group 2 includes FL carriers N₁+1 through N₁+N₂ and RL carrier2, and so on, and carrier group M includes FL carriers K−N_(M)+1 throughK and RL carrier M. In general, N₁ through N_(M) may be the same ordifferent. In an embodiment, N_(m)≦4, for m=1, . . . , M, and up to fourFL carriers may be associated with a single RL carrier in each carriergroup.

Multi-carrier structure 300 supports various system configurations. Aconfiguration with multiple FL carriers and multiple RL carriers may beused for high rate data transmission on both the forward and reverselinks. A configuration with multiple FL carriers and a single RL carriermay be used for high rate data transmission on the forward link. Aconfiguration with a single FL carrier and multiple RL carriers may beused for high rate data transmission on the reverse link. A suitableconfiguration may be selected for a terminal based on various factorssuch as the available system resources, data requirements, channelconditions, and so on.

In an embodiment, the FL and RL carriers have different significance.For each group, one (e.g., the first) FL carrier in the group isdesignated as a group FL primary, and each remaining FL carrier (if any)in the group is designated as a group FL auxiliary. One (e.g., thefirst) FL carrier among the K FL carriers is designated as a primary FLcarrier. Similarly, one (e.g., the first) RL carrier among the M RLcarriers is designated as a primary RL carrier.

A terminal may be assigned any number of FL carriers, one of which isdesignated as the primary FL carrier for that terminal. A terminal mayalso be assigned any number of RL carriers, one of which is designatedas the primary RL carrier for that terminal. Different terminals may beassigned different sets of FL and RL carriers. Furthermore, a giventerminal may be assigned different sets of FL and RL carriers over timebased on various factors such as those noted above.

In an embodiment, a terminal uses the primary FL and RL carriers for thefollowing functions:

Originate a call on the primary RL carrier,

Receive signaling during call setup on the primary FL carrier,

Perform Layer 3 signaling handoff procedure on the primary FL carrier,and

Select a serving base station for FL transmission based on the primaryFL carrier.

In an embodiment, the group FL primary in each carrier group controlsthe RL carrier in that group. The group FL primary may be used for thefollowing functions:

Send power control for the R-PICH,

Send rate control for the R-PDCH,

Send acknowledgements (on the F-ACKCH) for reverse link transmissions,

Send MAC control messages (on the F-PDCCH) to the terminal, and

Send forward grant messages (on the F-GCH) to the terminal.

The data and control channels in cdma2000 revision D are designed fordata transmission on a single carrier. Some of the control channels maybe modified to support data transmission on multiple carriers. Themodifications may be such that (1) the modified control channels arebackward compatible with the control channels in cdma2000 revision D and(2) the new changes may be easily implemented, e.g., in software and/orfirmware, which may reduce impact on hardware design.

A base station may transmit data on the forward link on any number of FLcarriers in any number of carrier groups to a terminal. In anembodiment, the RL carrier in each group carries the R-ACKCH and R-CQICHthat support all of the FL carriers in that group. In this embodiment,the R-ACKCH carries acknowledgements for packets received on the F-PDCHsfor all FL carriers in the group. The R-CQICH provides CQI feedback forall FL carriers in the group.

1. R-ACKCH

In another aspect, a new R-ACKCH structure that can support datatransmission on multiple FL carriers is described. A terminal may bemonitoring multiple FL carriers in a given group while transmitting on asingle RL carrier, as shown in FIG. 3. The terminal may receive multiplepackets on multiple F-PDCHs sent on these multiple FL carriers. Theterminal may acknowledge these multiple packets via a single R-ACKCHsent on the single RL carrier. The R-ACKCH may be designed with thecapability to carry acknowledgments for one or multiple packets,depending on the number of FL carriers being received.

FIG. 4A shows a block diagram of an R-ACKCH structure 410 used incdma2000 revision D. An R-ACKCH bit is generated in each 1.25 ms frame,which is one slot. This R-ACKCH bit may be (1) an ACK if a packet isdecoded correctly, (2) a NAK if a packet is decoded in error, or (3) anull bit if there is no packet to acknowledge. The R-ACKCH bit isrepeated 24 times by a symbol repetition unit 412 to generate 24identical modulation symbols, which are further processed andtransmitted on the R-ACKCH.

FIG. 4B shows a block diagram of an embodiment of a new R-ACKCHstructure 420 that can support up to four R-ACKCHs for up to four FLcarriers. The four R-ACKCHs may also be considered as four sub-channelsof a single R-ACKCH and may be called Reverse AcknowledgementSub-Channels (R-ACKSCHs). In the following description, theacknowledgement channel for each FL carrier is referred to as an R-ACKCHinstead of an R-ACKSCH.

FIG. 4B shows a case in which three R-ACKCHs are used for three FLcarriers, which are referred to as CDMA channels 0, 1 and 2. The R-ACKCHfor each CDMA channel is implemented with a respective set of signalpoint mapping unit 422, Walsh cover unit 424, and repetition unit 426.CDMA channels 0, 1 and 2 are assigned 4-chip Walsh codes of W₀ ⁴, W₁ ⁴and W₂ ⁴, respectively. The Walsh codes are also referred to as Walshfunctions or Walsh sequences and are defined in TIA/EIA IS-2000.2.

An R-ACKCH bit is generated in each 1.25 ms frame (or slot) for eachCDMA channel. For CDMA channel 0, signal point mapping unit 422 a mapsthe R-ACKCH bit for CDMA channel 0 to a value of +1, −1, or 0 dependingon whether the R-ACKCH bit is an ACK, a NAK, or a null bit,respectively. Walsh cover unit 424 a covers the mapped value with the4-chip Walsh code W₀ ⁴ assigned to CDMA channel 0. The Walsh covering isachieved by (1) repeating the mapped value four times and (2)multiplying the four identical values with the four chips of Walsh codeW₀ ⁴ to generate a sequence of four symbols. Repetition unit 426 arepeats the 4-symbol sequence six times and generates a sequence of 24symbols for CDMA channel 0. The processing for CDMA channels 1 and 2proceeds in similar manner as CDMA channel 0.

In each slot, a summer 428 sums the three 24-symbol sequences fromrepetition units 426 a, 426 b and 426 c for CDMA channels 0, 1 and 2,respectively, and provides 24 modulation symbols for the slot. Thesemodulation symbols are further processed and transmitted. A base stationis able to recover the R-ACKCH bit for each CDMA channel by performingthe complementary decovering with the Walsh code assigned to that CDMAchannel.

FIG. 4C shows a block diagram of an embodiment of a new R-ACKCHstructure 430 that can support up to eight R-ACKCHs, e.g., for up toeight FL carriers. FIG. 4C shows a case in which seven R-ACKCHs are usedfor seven FL carriers, which are referred to as CDMA channels 0 through6. The R-ACKCH for each CDMA channel is implemented with a respectiveset of signal point mapping unit 432, Walsh cover unit 434, andrepetition unit 436. CDMA channels 0 through 6 are assigned 8-chip Walshcodes of W₀ ⁸ through W₆ ⁸, respectively, which are defined in TIA/EIAIS-2000.2.

For each CDMA channel, signal point mapping unit 432 maps the R-ACKCHbit for that CDMA channel to a value of +1, −1, or 0. Walsh cover unit434 covers the mapped value with the 8-chip Walsh code assigned to thatCDMA channel and provides a sequence of eight symbols. Repetition unit436 repeats the 8-symbol sequence three times and generates a sequenceof 24 symbols for the CDMA channel. In each slot, a summer 438 sums theseven 24-symbol sequences from repetition units 436 a through 436 g forCDMA channels 0 through 6, respectively, and provides 24 modulationsymbols for the slot. These modulation symbols are further processed andtransmitted.

FIGS. 4B and 4C show exemplary R-ACKCH structures 420 and 430 thatsupport multiple R-ACKCHs and are backward compatible with the currentR-ACKCH structure 410 shown in FIG. 4A. If only one CDMA channel isbeing received, then the R-ACKCH bits for this CDMA channel may beprocessed with Walsh code W₀ ⁴ or W₀ ⁸, and the R-ACKCH bits for allother CDMA channels may be set to null bits. The output of summer 428 or438 would then be identical to the output of repetition unit 412 in FIG.4A. Additional CDMA channels may be supported by sending the R-ACKCHbits for these additional CDMA channels using other Walsh codes. Therepetition factor is reduced from 24 down to either 6 or 3 depending onthe Walsh code length.

The R-ACKCH structures shown in FIGS. 4B and 4C allow for recovery ofthe R-ACKCH bits using hardware designed for the R-ACKCH structure shownin FIG. 4A. The hardware may generate 24 received symbols for theR-ACKCHs in each slot. The decovering of these 24 received symbols withWalsh codes may be performed in software and/or firmware, which mayreduce the impact of upgrading a base station to support multi-carrieroperation.

Multiple R-ACKCHs may also be implemented with other structures, andthis is within the scope of the present invention. For example, multipleR-ACKCHs may be time division multiplexed and sent in differentintervals of a given slot.

2. R-CQICH

In yet another aspect, a new R-CQICH structure that can support CQIfeedback for multiple FL carriers is described. A terminal may bemonitoring multiple FL carriers in a given group while transmitting on asingle RL carrier, as shown in FIG. 3. These multiple FL carriers mayobserve different channel conditions (e.g., different fadingcharacteristics) and may achieve different received signal qualities atthe terminal. It is desirable for the terminal to provide CQI feedbackfor as many of the assigned FL carriers as possible so that the systemcan select the proper FL carrier(s) to send data as well as a suitablerate for each selected FL carrier. If the system configuration includesa single RL carrier, then the terminal may send CQI feedback for all FLcarriers on a single R-CQICH via the single RL carrier. The R-CQICH maybe designed with the capability to carry CQI feedback for one ormultiple FL carriers.

In cdma2000 revision D, the R-CQICH may operate in one of two modes, afull mode or a differential mode, in each 1.25 ms frame (or slot). Inthe full mode, a full CQI report composed of a 4-bit value is sent onthe R-CQICH. This 4-bit CQI value conveys the received signal qualityfor one CDMA channel. In the differential mode, a differential CQIreport composed of a 1-bit value is sent on the R-CQICH. This 1-bit CQIvalue conveys the difference in received signal quality between thecurrent and prior slots for one CDMA channel. The full and differentialCQI reports may be generated as described in TIA/EIA IS-2000.2.

FIG. 5A shows a block diagram of an R-CQICH structure 510 used incdma2000 revision D. A 4-bit or 1-bit CQI value may be generated in each1.25 ms frame (or slot) for a CDMA channel, depending on whether thefull or differential mode is selected. A 4-bit CQI value is alsoreferred to as a CQI value symbol. A 1-bit CQI value is also referred toas a differential CQI symbol. A 4-bit CQI value is encoded with a (12,4) block code by a block encoder 512 to generate a codeword with 12symbols. A 1-bit CQI value is repeated 12 times by a symbol repetitionunit 514 to generate 12 symbols. A switch 516 selects either the outputof block encoder 512 for the full mode or the output of repetition unit514 for the differential mode.

A CQI report may be sent to a specific base station by covering thereport with a Walsh code assigned to that base station. A Walsh coverunit 518 receives a 3-bit Walsh code for a base station selected toserve the terminal and generates a corresponding 8-chip Walsh sequence.Unit 518 also repeats the 8-chip Walsh sequence 12 times and provides 96Walsh chips in each slot. A modulo-2 adder 520 adds the symbols fromswitch 516 with the output of Walsh cover unit 518 and provides 96modulation symbols in each slot. Walsh cover unit 518 and adder 520effectively cover each symbol from switch 516 with the 3-bit Walsh codefor the selected base station. A signal point mapping unit 522 maps eachmodulation symbol to a value of +1 or −1. A Walsh cover unit 524 coverseach mapped value from unit 522 with a Walsh code of W₁₂ ¹⁶ and providesoutput symbols, which are further processed and transmitted on theR-CQICH.

The new R-CQICH structure can support the full and differential modesfor one or multiple FL carriers. In an embodiment, full CQI reports fordifferent FL carriers in a group are sent in different slots in a TDMmanner. In an embodiment, differential CQI reports for all FL carriersin the group for a given slot are jointly encoded and sent together inthe slot. The joint encoding of differential CQI reports is moreefficient than separate encoding of individual differential CQI reports.The repetition in block 514 is replaced by more efficient coding.

FIG. 5B shows a block diagram of an embodiment of a new R-CQICHstructure 530 that can provide CQI feedback for multiple CDMA channels.In this embodiment, a 4-bit CQI value for one CDMA channel is encodedwith a (12, 4) block code by a block encoder 532 to generate a codewordwith 12 symbols. N 1-bit CQI values for N CDMA channels are jointlyencoded with a (12, N) block code by a block encoder 534 to generate acodeword with 12 symbols. The rate (R) of a block code is equal to thenumber of input bits over the number of output bits, or R=4/12 for the(12, 4) block code and R=N/12 for the (12, N) block code. Different coderates generate different amounts of redundancy and require differentreceived signal qualities for reliable reception. Hence, differentamounts of transmit power may be used for the codeword from blockencoder 534 depending on the number of CDMA channels N.

A switch 536 selects either the output of block encoder 532 for the fullmode or the output of block encoder 534 for the differential mode. Thesymbols from switch 536 are processed by a Walsh cover unit 538, anadder 540, a signal point mapping unit 542, and a Walsh cover unit 544in the same manner described above for units 518, 520, 522 and 524,respectively, in FIG. 5A. Walsh cover unit 544 provides output symbols,which are further processed and transmitted on the R-CQICH.

The block coding by encoder 534 may be expressed in matrix form asfollows:y=u·G,  Eq(1)where

-   -   u=[u₀ u₁ . . . u_(k-1)] is a 1×k row vector for a sequence of        1-bit CQI values, with u₀ being the first input bit in vector u,    -   y=[y₀ y₁ . . . y_(n-1)] is a 1×n row vector for an encoder        output codeword, with y₀ being the first output bit in vector y,        and    -   G is a k×n generator matrix for the block coding.

The block codes are typically specified in terms of their generatormatrices. Different block codes may be defined for different values of Nfrom 2 through 7 to support up to 7 CDMA channels. The block code foreach value of N may be selected to achieve good performance, which maybe quantified by the minimum distance between codewords. Table 2 listsexemplary block codes for N=2 through 7. The block codes in Table 2 havethe largest possible minimum distance between codewords for linear blockcodes.

TABLE 2 Block Code Generator Matrix (12, 2)$\underset{\_}{G} = \begin{bmatrix}110 \\011\end{bmatrix}$ (12, 3) $\underset{\_}{G} = \begin{bmatrix}100110111100 \\010011011110 \\001001101111\end{bmatrix}$ (12, 4) $\underset{\_}{G} = \begin{bmatrix}000011111111 \\111100001111 \\001100110011 \\010101010101\end{bmatrix}$ (12, 5) $\underset{\_}{G} = \begin{bmatrix}101001110000 \\010100111000 \\001010011100 \\000101001110 \\000010100111\end{bmatrix}$ (12, 6) $\underset{\_}{G} = \begin{bmatrix}101110100000 \\010111010000 \\001011101000 \\000101110100 \\000010111010 \\000001011101\end{bmatrix}$ (12, 7) $\underset{\_}{G} = \begin{bmatrix}100111000000 \\010011100000 \\001001110000 \\000100111000 \\000010011100 \\000001001110 \\000000100111\end{bmatrix}$

The block coding for N=1 may correspond to the 12× bit repetitionperformed by unit 514 in FIG. 5A. In the embodiment shown in Table 2, a(12, 2) block code is composed of a (3, 2) block code followed by 4×sequence repetition. The generator matrix for the (12, 4) block code inencoder 534 is the same as the generator matrix for the (12, 4) blockcode in encoders 512 and 532. The (12, 2), (12, 3), (12, 4), (12, 5),(12, 6) and (12, 7) block codes in Table 2 have minimum distances of 8,6, 6, 4, 4 and 4, respectively. Other generator matrices may also bedefined and used for the block codes for the differential CQI reports.

FIG. 5B shows an exemplary R-CQICH structure 530 that supports CQIfeedback for multiple CDMA channels and is backward compatible with thecurrent R-CQICH structure 510 shown in FIG. 5A. If only one CDMA channelis being received, then the full CQI reports for this CDMA channel maybe processed with the (12, 4) block code, the differential CQI reportsmay be processed with 12× bit repetition, and the output of Walsh coverunit 544 would be identical to the output of Walsh cover unit 524 inFIG. 5A. Additional CDMA channels may be supported by (1) sending thefull CQI reports for the CDMA channels in different slots and (2)sending the differential CQI reports for the CDMA channels jointly inthe same slot.

The R-CQICH structure shown in FIG. 5B allows for recovery of the fulland differential CQI reports for multiple CDMA channels with littlechanges to the R-CQICH structure shown in FIG. 5A. The hardware for thephysical layer may perform block decoding for the full CQI reports. Thedemultiplexing of the full CQI reports for different CDMA channels maybe performed at a Medium Access Control (MAC) layer. The block decodingfor the differential CQI reports may be performed at the physical or MAClayer.

The R-CQICH for multiple CDMA channels may also be implemented withother structures, and this is within the scope of the present invention.For example, the full CQI reports for multiple CDMA channels may beblock encoded and sent in the same slot. As another example,differential CQI reports for a subset of the CDMA channels may be sentin a slot.

A terminal may be assigned multiple groups of FL and RL carriers, asshown in FIG. 3. For each carrier group, the R-CQICH sent on the RLcarrier in the group may carry CQI reports for the FL carriers in thegroup, as described above for FIG. 5B. The CQI reports may be sent invarious manners.

FIGS. 6A through 6E show some exemplary transmissions on the R-CQICH. Inthese figures, a full CQI report is represented by a taller box, and adifferential CQI report is represented by a shorter box. The height of abox roughly indicates the amount of transmit power used to send the CQIreport. The number(s) inside each box indicate the FL carrier(s) beingreported by the CQI report sent in that box.

FIG. 6A shows transmission of full and differential CQI reports for twoFL carriers 1 and 2 on the R-CQICH. In this example, a full CQI reportfor FL carrier 1 is sent in a slot, then differential CQI reports for FLcarriers 1 and 2 are sent in some number slots, then a full CQI reportfor FL carrier 2 is sent in a slot, then differential CQI reports for FLcarriers 1 and 2 are sent in some number slots, then a full CQI reportfor FL carrier 1 is sent in a slot, and so on. In general, the full CQIreports for each FL carrier may be sent at any rate, and the same ordifferent reporting rates may be used for the FL carriers. In anembodiment, a full CQI report is sent in one (e.g., the first) slot ofeach 20 ms frame and differential CQI reports are sent in the 15remaining slots in the frame. The full CQI reports for FL carriers 1 and2 may alternate as shown in FIG. 6A or may be multiplexed in othermanners.

FIG. 6B shows transmission of full CQI reports for two FL carriers 1 and2 on the R-CQICH. In this example, a full CQI report for FL carrier 1 issent in a slot, then a full CQI report for FL carrier 2 is sent in thenext slot, then a full CQI report for FL carrier 1 is sent in thefollowing slot, and so on.

FIG. 6C shows transmission of full and differential CQI reports forthree FL carriers 1, 2 and 3 on the R-CQICH with a repetition factor oftwo, or REP=2. In this example, a full CQI report for FL carrier 1 issent in the first two slots of a 20 ms frame, then differential CQIreports for FL carriers 1, 2 and 3 are sent in each remaining slot inthe frame, then a full CQI report for FL carrier 2 is sent in the firsttwo slots of the next 20 ms frame, then differential CQI reports for FLcarriers 1, 2 and 3 are sent in each remaining slot in the frame, then afull CQI report for FL carrier 3 is sent in the first two slots of thefollowing 20 ms frame, then differential CQI reports for FL carriers 1,2 and 3 are sent in each remaining slot in the frame, then a full CQIreport for FL carrier 1 is sent in the first two slots of the next 20 msframe, and so on. A differential CQI report may be sent in twoconsecutive slots, similar to the full CQI report, or may be sent in asingle slot.

FIG. 6D shows transmission of full CQI reports for three FL carriers 1,2 and 3 on the R-CQICH with a repetition factor of two. In this example,a full CQI report for FL carrier 1 is sent in two slots, then a full CQIreport for FL carrier 2 is sent in the next two slots, then a full CQIreport for FL carrier 3 is sent in the following two slots, then a fullCQI report for FL carrier 1 is sent in the next two slots, and so on.

FIG. 6E shows transmission of full CQI reports for three FL carriers 1,2 and 3 on the R-CQICH with a repetition factor of two and two switchslots. In this example, the full CQI reports for FL carriers 1, 2 and 3are sent in the manner described above for FIG. 6D. However, the lastfour slots in the 20 ms frame are used to send a switch slot pattern(denoted as “s” in FIG. 6E), which is a message to switch to a newserving base station.

As shown in FIGS. 6A through 6E, the time division multiplexing of thefull CQI reports for all FL carriers results in the reporting rate forthe full CQI reports for a given FL carrier decreasing as the number ofFL carriers in a group increases. For example, if a group includes 7 FLcarriers, then a full CQI report may be sent at a rate of once every7×20 ms=140 ms for each FL carrier. The joint encoding of thedifferential CQI reports for all FL carriers results in the reportingrate for the differential CQI reports being independent of, andunaffected by, the number of FL carriers in the group. When switching toa new cell, the switch slot pattern “punctures” (or replaces) the fullCQI reports. This puncturing may not equally impact all FL carriers. Inthe example shown in FIG. 6E, the switch slot pattern impacts FLcarriers 1 and 2 but not FL carrier 3.

In an embodiment, a terminal selects a single base station for datatransmission on the forward link. This single base station may beselected based on received signal qualities measured at the terminal forthe primary FL carrier, all assigned FL carriers, or a subset of theassigned FL carriers. The R-CQICHs for all RL carriers use the Walshcover for the selected base station and hence point to the same cell.The selection of a single base station avoids out-of-order transmissionson the forward link and its potential negative impact on Radio LinkProtocol (RLP). In the forward direction, RLP frames are typicallypre-packed at a Base Station Controller (BSC) and then forwarded to abase station for transmission to the terminal. Hence, out-of-ordertransmission of RLP frames may be avoided by transmitting from a singlebase station.

In another embodiment, a terminal may select multiple base stations fordata transmission on the forward link. Since fading characteristics maybe different for different FL carriers, as noted above, this embodimentallows the terminal to select a suitable base station for each FLcarrier or each group of FL carriers, which may improve the overallthroughput.

3. R-PICH

It is desirable to reduce reverse link overhead for data transmission onthe forward link. This may be achieved by assigning a terminal with asingle carrier group composed of multiple FL carriers and a single RLcarrier. Data may be sent on the multiple FL carriers, andacknowledgements and CQI feedback may be efficiently sent on the singleRL carrier.

In certain instances, multiple RL carriers may be utilized. For example,a base station may not support the new R-ACKCH and R-CQICH structuresdescribed above. In this case, each FL carrier may be associated withone RL carrier that supports the R-ACKCH and R-CQICH for that FLcarrier.

In cdma2000 revision D, a terminal transmits a pilot on the R-PICH toassist a base station in detecting a reverse link transmission. If asingle RL carrier is assigned, then the pilot overhead is shared amongall FL carriers associated with this RL carrier. However, if multiple RLcarriers are assigned and if the R-PICH is sent on each RL carrier tosupport the R-ACKCH and R-CQICH, then the pilot overhead may besignificant for such low data rate on the reverse link. A reduction inpilot overhead may be achieved by using a control-hold mode.

FIG. 7 shows transmission of full and gated pilots on the R-PICH. A fullpilot is a pilot transmission in each slot and is referred to as pilotgating rate 1. The control-hold mode defined in cdma2000 revision D (orsimply, the “Rev D control-hold mode”) supports pilot gating rates of ½and ¼. As shown in FIG. 7, a gated pilot is a pilot transmission in someof the slots, or more specifically in every other slot for pilot gatingrate of ½ and every fourth slot for pilot gating rate of ¼.

In cdma2000 revision D, a base station places a terminal in thecontrol-hold mode by sending a Layer 3 message, typically afterexpiration of a control-hold timer. For example, if the base stationdoes not receive any data from and does not send any data to theterminal for a particular time period, then the base station may send aLayer 3 message to the terminal to place it in the control-hold mode.The arrival of new data at either the base station or the terminaltriggers a transition out of the control-hold mode. If the new dataarrives at the terminal, then the terminal autonomously transitions outof the control-hold mode and starts transmitting full pilot along withdata on the reverse link. The base station detects the transition out ofthe control-hold mode by the terminal and decodes the data sent with thefull pilot. If the new data arrives at the base station, then the basestation first wakes up the terminal by sending a MAC message on theF-PDCCH. While in the control-hold mode, the terminal does not processthe F-PDCH in order to conserve power.

Many applications are characterized by asymmetric data traffic, andmultiple F-PDCHs on multiple FL carriers may be desirable for theseapplications. As a consequence, multiple reverse pilots may need to besent on multiple RL carriers to support the multiple F-PDCHs. Besidesthe reverse pilots, the traffic on the auxiliary RL carriers may consistof only CQI reports on the R-CQICH and acknowledgements on the R-ACKCH.In such a scenario, the use of the control-hold mode may significantlyreduce reverse link overhead on the auxiliary RL carriers.

However, the Rev D control-hold mode is not directly applicable for theauxiliary RL carriers for the following reasons. First, the terminaldoes not decode the F-PDCH while in the Rev D control-hold mode. Second,the terminal is required to transition out of the Rev D control-holdmode before transmitting on the R-ACKCH, and a Layer 3 message from thebase station is needed to put the terminal back in the control-holdmode. It is undesirable to have to send the Layer 3 message each timethe terminal transmits on the R-ACKCH. Furthermore, since the basestation sends the Layer 3 message after the control-hold timer expires(which is typically on the order of few hundred milliseconds), the fullpilot is transmitted on the reverse link during this time.

In yet another aspect, an “auxiliary” control-hold mode is defined foruse on an auxiliary RL carrier. In an embodiment, the auxiliarycontrol-hold mode differs from the Rev D control-hold mode in thefollowing manners:

-   -   The terminal can process the F-PDCH while in the auxiliary        control-hold mode,    -   The terminal can transmit acknowledgements on the R-ACKCH        without transitioning out of the auxiliary control-hold mode,    -   If the F-PDCH is successfully decoded, then the terminal can        autonomously transmit full pilot along with the acknowledgements        on R-ACKCH, and    -   The terminal can resume pilot gating after completing the        R-ACKCH transmission.        The auxiliary control-hold mode may also be defined with        different and/or additional features.

To reduce pilot overhead on the reverse link, the Rev D control-holdmode may be used on the primary RL carrier, and the auxiliarycontrol-hold mode may be used on each auxiliary RL carrier. The twoversions of the control-hold mode can support efficient operation ofmultiple RL carriers for multi-carrier operation.

In an embodiment, the control-hold mode may be independently defined foreach RL carrier. The following scenarios are possible:

-   -   The primary RL carrier is in an active mode and any number of        auxiliary RL carriers may be in the control-hold mode. The        terminal can process the F-PDCH for the auxiliary RL carriers        and can transmit on the R-ACKCH without leaving the control-hold        mode.    -   All RL carriers are in the control hold mode. The terminal does        not process the F-PDCH and does not transmit on the R-ACKCH        without leaving the control-hold mode. This is a power        conserving mode.

4. R-REQCH

A terminal may send various types of information on the R-REQCH to abase station. The triggers for sending R-REQCH messages in cdma2000revision D may also be used as the triggers for sending R-REQCH messagesfor multi-carrier operation. In an embodiment, a terminal sends R-REQCHmessages on the primary RL carrier to convey service related informationto a base station. A single buffer may be maintained per service fordata transmission on all RL carriers. The service related informationmay include buffer size and watermark crossing. In an embodiment, theterminal sends R-REQCH messages on both the primary and auxiliary RLcarriers to convey power headroom for these RL carriers. A power reporttrigger for each RL carrier may be used to send R-REQCH messages toconvey the power headroom for that RL carrier.

5. Scheduling

The scheduling of terminals for data transmission on the forward andreverse links may be performed in various manners. The scheduling may becentralized for multiple carriers or distributed for each carrier. In anembodiment, a centralized scheduler schedules terminals for datatransmission across multiple carriers. The centralized scheduler maysupport flexible scheduling algorithms that can exploit CQI informationacross all carriers in order to improve throughput and/or provide thedesired quality of service (QoS). In another embodiment, a distributedscheduler is provided for each carrier and schedules terminals on thatcarrier. The distributed schedulers for different carriers may operateindependently of one another and may reuse existing schedulingalgorithms for cdma2000 revision D.

A terminal may be assigned multiple carriers that may be supported by asingle channel card or multiple channel cards at a base station. Ifmultiple FL carriers are handled by different channel cards, then thereis a channel card communication delay, which may be on the order ofseveral milliseconds. Even though this delay is small, it is typicallylarger than 1.25 ms, which is the time to decode the R-ACKCH, andpreferably to also decode the R-CQICH, and to schedule a newtransmission on the F-PDCH.

The centralized scheduler may incur additional scheduling delay ifmultiple channel cards are used for different FL carriers. Thisadditional delay is composed of two components. The first component isR-CQICH delay to propagate the CQI feedback from the channel card thatis handling the reverse link decoding to the centralized scheduler. Thesecond component is the delay for the selected encoder packet to reachthe channel card that is handling the F-PDCH transmission. Theadditional delay may impact system throughput, but its effect should belimited to a relatively narrow range of velocities and channel models.

The distributed schedulers may not incur the additional delay describedabove for the centralized scheduler, e.g., if the reverse link decodingand the forward link transmission are handled by a single channel card.This is feasible if there are no auxiliary FL carriers in a carriergroup. However, if a distributed scheduler is implemented on eachchannel card, then a separate buffer may be maintained for each channelcard so that the data can be co-located with the scheduler. This cardbuffer may be small, and a larger buffer may be located elsewhere at thebase station. The distributed scheduler should have enough data on handto schedule traffic. The delay to obtain extra data from the largerbuffer may be on the order of several milliseconds. The card buffer sizeshould take into account the highest possible over-the-air data rate inorder to avoid buffer underflow. Even though the buffers at the channelcards may be relatively small, there is greater possibility forout-of-order RLP frame reception at a terminal. Hence, a longerdetection window may be used for RLP frames. Conventional early NAKingtechniques are not useful because they do not account for the fact thattraffic may be out of order even in the first transmission. The longerdelay detection window in RLP may have greater impact on TCP. MultipleRLP instances, e.g., one per F-PDCH, may be used but may createout-of-order arrival of TCP segments.

RLP frames are commonly pre-packed at a BSC and appended with MUXoverhead. Each RLP frame, including the MUX overhead, contains 384 bitsin cdma2000 and is identified by a 12-bit sequence number. The cdma2000RLP header allocates 12 bits for the RLP frame sequence numbers, whichare used to re-assemble the RLP frames at a terminal. Given such a smallRLP frame size, the sequence space may be inadequate at high rates, suchas the ones achievable in multi-carrier configurations. To support highdata rates with the existing RLP, the RLP frames may be pre-segmented sothat the additional 12 bits of sequence space that are used forsegmented RLP frames may be reused. Sequence space is not an issue onthe reverse link, since RLP frames do not need to be pre-packed.

A call setup procedure for multi-carrier operation may be implemented asfollows. A terminal acquires system information from a Forward SyncChannel (F-SYNCH) and obtains overhead messages from a Forward PagingChannel (F-PCH) or a Forward Broadcast Control Channel (F-BCCH) sent onthe primary FL carrier. The terminal then originates a call on theprimary RL carrier. A base station may assign a traffic channel to theterminal via an Extended Channel Assignment Message (ECAM) sent on theprimary FL carrier. The terminal acquires the traffic channel andtransitions to a Mobile Station Control on the Traffic Channel state,which is one of the mobile station operating states in cdma2000. In anembodiment, the operating states are defined for only the primarycarriers. The base station may thereafter assign multiple FL and RLcarriers, e.g., via a Universal Handoff Direction Message (UHDM). Wheninitializing a traffic channel on a new carrier, the base station maystart transmitting commands on a Forward Common Power Control Channel(F-CPCCH) after sending the UHDM. The terminal may start transmittingthe R-PICH upon receiving the UHDM. The terminal may send a HandoffCompletion Message (HCM), which is a cdma2000 Layer 3 protocol message,on the primary RL carrier to the base station to signal acquisition ofthe F-CPCCH.

6. Flows and System

FIG. 8 shows an embodiment of a process 800 performed by a terminal formulti-carrier operation. The terminal receives an assignment of multipleforward link (FL) carriers and at least one reverse link (RL) carrier(block 812). The terminal may receive data transmission on one or moreof the multiple FL carriers (block 814). The terminal may demodulate anddecode the received data transmission for each FL carrier separately(block 816). The terminal may also transmit data on the at least one RLcarrier (block 818). The terminal may be scheduled for data transmissionon the forward and/or reverse link based on various factors such as theavailability of system resources, the amount of data to send, thechannel conditions, and so on.

The terminal may send designated RL signaling on a primary RL carrier,which may be designated from among the at least one RL carrier (block820). The terminal may receive designated FL signaling on a primary FLcarrier, which may be designated from among the multiple FL carriers(block 822). For example, the terminal may originate a call on theprimary RL carrier and may receive signaling for call setup on theprimary FL carrier. The terminal may select a base station for datatransmission on the forward link based on the received signal qualityfor the primary FL carrier.

The multiple FL carriers and the at least one RL carrier may be arrangedin at least one group. Each group may include at least one FL carrierand one RL carrier, as shown in FIG. 3. The terminal may receive packetson the FL carrier(s) in each group and may send acknowledgements for thereceived packets via the RL carrier in that group. The terminal may alsosend CQI reports for the FL carrier(s) in each group via the RL carrierin that group. One FL carrier in each group may be designated as a groupprimary FL carrier. The terminal may receive signaling for the RLcarrier in each group via the group primary FL carrier.

FIG. 9 shows an embodiment of a process 900 for sendingacknowledgements. A terminal receives packets on multiple data channels(e.g., F-PDCHs) sent via multiple forward link (FL) carriers (block912). The terminal determines acknowledgements for the packets receivedon the data channels (block 914). The terminal channelizes theacknowledgement for each data channel with an orthogonal code (e.g., aWalsh code) assigned to that data channel to generate a symbol sequencefor the data channel (block 916). The terminal replicates the symbolsequence for each data channel multiple times (block 918). The terminalgenerates modulation symbols for an acknowledgement channel (e.g.,R-ACKCH) based on the replicated symbol sequences for the multiple datachannels (block 920).

The number of data channels may be configurable. An orthogonal code ofall zeros or all ones may be used if acknowledgements are being sent foronly one data channel, e.g., for backward compatibility with cdma2000revision D. Orthogonal codes of a first length (e.g., four chips) may beused if the number of data channels is less than a first value (e.g.,four). Orthogonal codes of a second length (e.g., eight chips) may beused if the number of data channels is equal to or greater than thefirst value. The repetition factor may also be dependent on the numberof data channels.

FIG. 10 shows an embodiment of a process 1000 for sending channelquality indication (CQI) reports. A terminal obtains full CQI reportsfor multiple forward link (FL) carriers, with each full CQI reportindicative of then received signal quality for one FL carrier (block1012). The terminal channelizes each full CQI report with an orthogonalcode (e.g., a Walsh code) for a selected base station (block 1014). Theterminal sends the full CQI reports for the multiple FL carriers indifferent time intervals (or slots) on a CQI channel (block 1016). Theterminal may cycle through the multiple FL carriers, select one FLcarrier at a time, and send a full CQI report for each selected FLcarrier in a time interval designated for sending full CQI report.

The terminal obtains differential CQI reports for the multiple FLcarriers for a particular time interval (block 1018). The terminaljointly encodes the differential CQI reports for the multiple FLcarriers to obtain a codeword (block 1020). The terminal may select ablock code based on the number of FL carriers and may jointly encode thedifferential CQI reports with the selected block code. The terminalchannelizes the codeword with the orthogonal code for the selected basestation (block 1022). The terminal then sends the codeword on the CQIchannel in the particular time interval (block 1024).

FIG. 11 shows an embodiment of a process 1100 for reducing pilotoverhead, e.g., for multi-carrier operation. A terminal operates in acontrol-hold mode that allows for transmission of a gated pilot (block1112). The terminal receives a data channel (e.g., F-PDCH) sent on theforward link while in the control-hold mode (block 1114). The terminaltransmits a gated pilot on the reverse link if no other transmissionsare being sent on the reverse link (block 1116). The terminal transmitsa full pilot on the reverse link if a transmission is being sent on thereverse link (block 1118). For example, the terminal may generateacknowledgements for packets received on the data channel, send theacknowledgements along with the full pilot on the reverse link, andresume transmitting the gated pilot after completing the transmission ofthe acknowledgements on the reverse link. The terminal transitions outof the control-hold mode in response to an exit event, which may bereception of signaling to exit the control-hold mode, transmission ofdata on the reverse link, and so on (block 1120).

FIGS. 8 through 11 show processes performed by a terminal formulti-carrier operation. A base station performs the complementaryprocessing to support multi-carrier operation.

FIG. 12 shows a block diagram of an embodiment of a base station 110 anda terminal 120. For the forward link, at base station 110, an encoder1210 receives traffic data and signaling for terminals. Encoder 1210processes (e.g., encodes, interleaves, and symbol maps) the traffic dataand signaling and generates output data for various forward linkchannels, e.g., the F-PDCH, F-PDCCH, F-ACKCH and F-GCH. A modulator 1212processes (e.g., channelizes, spectrally spreads, and scrambles) theoutput data for the various forward link channels and generates outputchips. A transmitter (TMTR) 1214 conditions (e.g., converts to analog,amplifies, filters, and frequency upconverts) the output chips andgenerates a forward link signal, which is transmitted via an antenna1216.

At terminal 120, an antenna 1252 receives the forward link signal frombase station 110 as well as signals from other base stations andprovides a received signal to a receiver (RCVR) 1254. Receiver 1254conditions (e.g., filters, amplifies, frequency downconverts, anddigitizes) the received signal and provides data samples. A demodulator(Demod) 1256 processes (e.g., descrambles, despreads, and dechannelizes)the data samples and provides symbol estimates. In an embodiment,receiver 1254 and/or demodulator 1256 perform filtering to pass all FLcarriers of interest. A decoder 1258 processes (e.g., demaps,deinterleaves, and decodes) the symbol estimates and provides decodeddata for the traffic data and signaling sent by base station 110 toterminal 120. Demodulator 1256 and decoder 1258 may perform demodulationand decoding separately for each FL carrier.

On the reverse link, at terminal 120, an encoder 1270 processes trafficdata and signaling (e.g., acknowledgements and CQI reports) andgenerates output data for various reverse link channels, e.g., theR-PDCH, R-ACKCH, R-CQICH, R-PICH and R-REQCH. A modulator 1272 furtherprocesses the output data and generates output chips. A transmitter 1274conditions the output chips and generates a reverse link signal, whichis transmitted via antenna 1252. At base station 110, the reverse linksignal is received by antenna 1216, conditioned by a receiver 1230,processed by a demodulator 1232, and further processed by a decoder 1234to recover the data and signaling sent by terminal 120.

Controllers/processors 1220 and 1260 direct the operation at basestation 110 and terminal 120, respectively. Memories 1222 and 1262 storedata and program codes for controllers/processors 1220 and 1260,respectively. A scheduler 1224 may assign FL and/or RL carriers toterminals and may schedule the terminals for data transmission on theforward and reverse links.

The multi-carrier transmission techniques described herein have thefollowing desirable characteristics:

-   -   Multi-carrier forward link that is backward compatible with Rev        D forward link—no changes to the Rev D physical layer,    -   Multi-carrier reverse link that is backward compatible with Rev        D reverse link—new backward compatible R-ACKCH and R-CQICH        structures that should not impact hardware implementation, and    -   Flexible configurable system—K FL carriers and M RL carriers,        where K≦N×M and K≧M.

The transmission techniques described herein may provide variousadvantages. First, the techniques allow cdma2000 revision D to supportmultiple carriers using only or mostly software/firmware upgrade.Relatively minor changes are made to some RL channels (e.g., the R-ACKCHand R-CQICH) to support multi-carrier operation. These changes may behandled by software/firmware upgrade at the base stations so thatexisting hardware such as channel cards may be reused. Second, higherpeak data rates may be supported on the forward and reverse links.Third, the use of multiple F-PDCHs on multiple FL carriers may improvediversity, which may improve QoS. The flexible carrier structure allowsgradual increase in data rates with advances in VLSI technology.

Headings are included herein for reference and to aid in locatingcertain sections. These headings are not intended to limit the scope ofthe concepts described therein under, and these concepts may haveapplicability in other sections throughout the entire specification.

Those of skill in the art would understand that information and signalsmay be represented using any of a variety of different technologies andtechniques. For example, data, instructions, commands, information,signals, bits, symbols, and chips that may be referenced throughout theabove description may be represented by voltages, currents,electromagnetic waves, magnetic fields or particles, optical fields orparticles, or any combination thereof.

Those of skill would further appreciate that the various illustrativelogical blocks, modules, circuits, and algorithm steps described inconnection with the embodiments disclosed herein may be implemented aselectronic hardware, computer software, or combinations of both. Toclearly illustrate this interchangeability of hardware and software,various illustrative components, blocks, modules, circuits, and stepshave been described above generally in terms of their functionality.Whether such functionality is implemented as hardware or softwaredepends upon the particular application and design constraints imposedon the overall system. Skilled artisans may implement the describedfunctionality in varying ways for each particular application, but suchimplementation decisions should not be interpreted as causing adeparture from the scope of the present invention.

The various illustrative logical blocks, modules, and circuits describedin connection with the embodiments disclosed herein may be implementedor performed with a general purpose processor, a digital signalprocessor (DSP), an application specific integrated circuit (ASIC), afield programmable gate array (FPGA) or other programmable logic device,discrete gate or transistor logic, discrete hardware components, or anycombination thereof designed to perform the functions described herein.A general-purpose processor may be a microprocessor, but in thealternative, the processor may be any conventional processor,controller, microcontroller, or state machine. A processor may also beimplemented as a combination of computing devices, e.g., a combinationof a DSP and a microprocessor, a plurality of microprocessors, one ormore microprocessors in conjunction with a DSP core, or any other suchconfiguration.

The steps of a method or algorithm described in connection with theembodiments disclosed herein may be embodied directly in hardware, in asoftware module executed by a processor, or in a combination of the two.A software module may reside in RAM memory, flash memory, ROM memory,EPROM memory, EEPROM memory, registers, hard disk, a removable disk, aCD-ROM, or any other form of storage medium known in the art. Anexemplary storage medium is coupled to the processor such that theprocessor can read information from, and write information to, thestorage medium. In the alternative, the storage medium may be integralto the processor. The processor and the storage medium may reside in anASIC. The ASIC may reside in a user terminal. In the alternative, theprocessor and the storage medium may reside as discrete components in auser terminal.

The previous description of the disclosed embodiments is provided toenable any person skilled in the art to make or use the presentinvention. Various modifications to these embodiments will be readilyapparent to those skilled in the art, and the generic principles definedherein may be applied to other embodiments without departing from thespirit or scope of the invention. Thus, the present invention is notintended to be limited to the embodiments shown herein but is to beaccorded the widest scope consistent with the principles and novelfeatures disclosed herein.

The invention claimed is:
 1. An apparatus for improving capacity forhigh data rate transmission in a wireless communication systemcomprising: at least one processor configured to receive an assignmentof multiple downlink carriers from a base station comprising one or morepacket data channels (PDCH) and at least one uplink carrier, andthereafter to receive data transmission on one or more of the multipledownlink carriers, wherein the assignment of the multiple downlinkcarriers is based on one of a transmission channel, a desired datatransmission rate, and available transmission resources; and the atleast one processor further configured to sendacknowledgement/non-acknowledgement information over one uplink carrierrelated to the multiple downlink carriers, and to report the quality ofthe one or more packet data channels over the at least one uplinkcarrier; and a memory coupled to the at least one processor.
 2. Theapparatus of claim 1, wherein at least one processor is configured tosend the acknowledgement/non-acknowledgement information over adedicated acknowledgement channel using the at least one uplink carrier.3. The apparatus of claim 1, wherein the at least one processor isconfigured to separately demodulate and decode the received datatransmission for each downlink carrier.
 4. The apparatus of claim 1,wherein the at least one processor is configured to send designateduplink signaling on a primary uplink carrier among the at least oneuplink carrier, and to receive designated downlink signaling on aprimary downlink carrier among the multiple downlink carriers.
 5. Theapparatus of claim 4, wherein the at least one processor is configuredto originate a call on the primary uplink carrier and to receivesignaling for call setup on the primary downlink carrier.
 6. Theapparatus of claim 4, wherein the at least one processor is configuredto select a base station for data transmission on forward link based onreceived signal quality for the primary downlink carrier.
 7. Theapparatus of claim 1, wherein the multiple downlink carriers and the atleast one uplink carrier are arranged in at least one group, each groupincluding at least one downlink carrier and one uplink carrier.
 8. Theapparatus of claim 7, wherein the at least one processor is configuredto receive packets on the at least one downlink carrier in each groupand to send acknowledgement/non-acknowledgment information for receivedpackets in each group via the uplink carrier in the group.
 9. Theapparatus of claim 7, wherein the at least one processor is configuredto report the quality of at least one downlink carrier in each group viathe uplink carrier in the group.
 10. The apparatus of claim 7, whereinone downlink carrier in each group is designated as a group primarydownlink carrier, and wherein the at least one processor is configuredto receive signaling for the uplink carrier in each group via the groupprimary downlink carrier.
 11. A method for improving capacity for highrate data transmission in a wireless communication system comprising:receiving an assignment of multiple downlink carriers from a basestation comprising one or more packet data channels (PDCH) and at leastone uplink carrier wherein the assignment of the multiple downlinkcarriers is based on one of a transmission channel, a desired datatransmission rate, and available transmission resources; receiving datatransmission on one or more of the multiple downlink carriers from thebase station; sending acknowledgement/non-acknowledgement information tothe base station over one uplink carrier related to the multipledownlink carriers; and reporting the quality of the one or more packetdata channels to the base station over the at least one uplink carrier.12. The method of claim 11, wherein theacknowledgement/non-acknowledgement information is sent over a dedicatedacknowledgement channel using the at least one uplink carrier.
 13. Themethod of claim 11, wherein the multiple downlink carriers and the atleast one uplink carrier are arranged in at least one group, each groupincluding at least one downlink carrier and one uplink carrier.
 14. Anapparatus for improving the capacity for high data rate transmission ina wireless communication system with a structure for higher data ratescomprising: means for receiving an assignment of multiple downlinkcarriers from a base station comprising one or more packet data channels(PDCH) and at least one uplink carrier wherein the assignment of themultiple downlink carriers is based on one of a transmission channel, adesired data transmission rate, and available transmission resources;means for receiving data transmission on one or more of the multipledownlink carriers from the base station; means for sendingacknowledgement/non-acknowledgement information to the base station overone uplink carrier related to the multiple downlink carriers; and meansfor reporting the quality of the one or more packet data channels to thebase station over the at least one uplink carrier.
 15. The apparatus ofclaim 14, wherein the means for sendingacknowledgement/non-acknowledgement information is configured to sendthe information over a dedicated acknowledgement channel using the atleast one uplink carrier.
 16. The apparatus of claim 14, wherein themultiple downlink carriers and the at least one uplink carrier arearranged in at least one group, each group including at least onedownlink carrier and one uplink carrier.
 17. The apparatus of claim 16,further comprising: means for reporting the quality of the one or morepacket data channels to the base station over the at least one uplinkcarrier is further configured to report for the at least one downlinkcarrier in each group via the uplink carrier in the group.
 18. Anon-transitory computer readable medium configured for improving thecapacity for high data rate transmission in a wireless communicationsystem with a structure for higher data rates, the medium storinginstructions operable to: receive an assignment of multiple downlinkcarriers from a base station comprising one or more packet data channels(PDCH) and at least one uplink carrier wherein the assignment of themultiple downlink carriers is based on one of a transmission channel, adesired data transmission rate, and available transmission resources;receive data transmission on one or more of the multiple downlinkcarriers from the base station; send acknowledgement/non-acknowledgementinformation to the base station over one uplink carrier related to themultiple downlink carriers; and report the quality of the one or morepacket data channels to the base station over the at least one uplinkcarrier.
 19. The non-transitory computer readable medium of claim 18,wherein the medium further stores instructions operable for sending theacknowledgement/non-acknowledgement information over a dedicatedacknowledgement channel using the at least one uplink carrier.
 20. Thenon-transitory computer readable medium of claim 18, wherein the mediumfurther stores instructions operable for arranging the multiple downlinkcarriers and the at least one uplink carrier in at least one group, eachgroup including at least one downlink carrier and one uplink carrier.21. The non-transitory computer readable medium of claim 20, wherein theinstructions operable for reporting the quality of the one or morepacket data channels to the base station over the at least one uplinkcarrier are further configured to report for the at least one downlinkcarrier in each group via the uplink carrier in the group.